The specific aims of our research are (1)\to purify the intracellular and secreted forms of human chorionic gonadotropin (hCG) subunits produced by malignant trophoblastic cells and normal placenta, (2)\to characterize biochemically the intracellular and secreted forms of hCG subunits produced by these tissues and, (3)\to determine the rate-limiting steps involved in the processing and secretion of hCG subunits by these tissues. Methods include pulse-chase labeling of cultured trophoblastic cell lines and organ cultures of normal placenta with radioactive amino acids and carbohydrates, determination of carbohydrate structure and amino acid composition, and sequence analysis of the glycoprotein subunits of hCG produced by these tissues. We have found that (1)\free hCG-beta subunit is present in media from cultured choriocarcinoma cells and placental explants and in the sera of patients with choriocarcinoma, (2)\an unusual beta-like substance is produced by cervical carcinoma cells, and (3)\there is a pH gradient, apparently within the Golgi apparatus, that regulates the oligosaccharide processing and secretion of hCG and its free subunits. Our long-term objectives are (1)\to learn what controls the secretion of hCG from normal and malignant trophoblastic cells, (2)\to determine what differences, if any, exist between the glycoprotein hormone subunits produced by normal and malignant cells, and (3)\to determine if the secretion of hCG subunits by trophoblastic cells can be pharmacologically manipulated. The results of these studies will have potential significance for the use of hCG subunits as tumor markers and in fertility control.